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The thermal performance of a Parabolic Trough Solar Power Plant (PTSPP) is critical to the overall efficiency of the system. The advancement of this technologies has led to the development of steam production and efficient solution that utilizes the sun’s energy for thermal power generation. In this work a parabolic trough concentrator with aperture area of 10.8 m2 was designed and evaluated in the Research and Technology Center of Energy (CRTEn) in Tunisia. This type of concentrating solar power collector is analyzed for indirect steam generating system. Several parameters, as thermal characterization of absorber; thermal efficiency of mixed heat exchangers; thermal efficiency, concentration ratio and quantification of steam generation, were considered in order to study their effects on energy efficiency. Experimental results show that the receiver of parabolic trough concentrator extracts 552.73 W of absorbed energy. We found that the thermal energy efficiency varies from 24% to 28% for PTSPP system and reach an average concentration factor around 200. As results, the maximum value of the steam generated by parabolic trough concentrator is 8 kg/h.

With the advanced ICT (information and communication technology) support, the local energy trading rapidly develops and plays an important role in energy supply in recent years. Because the demand and supply directly occurs at local level, the transmission cost saves a lot and the distributed renewables energy resources are capable to be used in energy supply. This paper presents a multi-supplier trading system for the local power market, which is formulated as a non-cooperative Cournot game. In this model, four types of providers: thermal power plant, wind power plant, PV power generation and customer-operated storage electricity supplier are considered separately. Their cost functions have been extensively formulated. A unique Nash equilibrium (NE) exists and the optimum strategies can be derived as demonstrated in a typical local market. The proposed approach can effectively model local energy trading of different types of energy providers.

Seeking for a low-cost carbon capture method and recovering waste heat of the flue gas are the effective ways to improve the thermal efficiency of power plants with carbon capture. A novel oxy-fuel combustion nature gas (NG) power plant integrated the gas turbine (GT), N2 Brayton cycle (NBC), Organic Rankine cycle (ORC), CO2 capture and cold energy utilization of liquefied natural gas (LNG) is proposed in this paper. NBC combined with GT to generate electricity can simplify heat transfer process and provide a utilization path of N2 to reduce the cost of air separation unit (ASU). ORC is used to recover low temperature waste heat of the sulfur-free flue gas with improving system efficiency. LNG cold energy is utilized to achieve low-cost carbon capture. O2/CO2 combustion and O2/H2O combustion are investigated to determine the suitable diluent. The result shows that GT and NBC have better performance in the O2/CO2 cycle compared to O2/H2O cycle, while ORC is more potential in the O2/H2O cycle. Taking into account the energy consumption of ASU and CO2 capture, the result shows that the liquid H2O is not suitable to be used to moderate the combustion temperature because the recycled H2O is vaporized in the combustor and consumes a large amount of heat. In the O2/CO2 atmosphere, the net power generation efficiency of integrated system can reach 56.57%.

China and the United States respectively adopted desulfurization electricity price and emission trading to achieved the effective sulfur dioxide emissions reduction in thermal power industry. By the methodology of cost-benefit analysis and comparative analysis with the United States, this paper analyzed the coal-fired power plants’ desulfurization cost, benefit, and social emission reduction cost of China’s desulfurization electricity price policy. The main findings are, the results of cost-benefit analysis show that China’s policy against the polluter pays principle, polluters can get benefit from this policy. Second, in terms of the cost of emission reduction, China’s cost is very high with 5.52 billion U.S. dollars in 2000 while the USA only cost 0.5-2.0 billion US dollars. Also, compared with the decreasing social cost of the United States, the China desulfurization electricity price policy leads the social SO2 reduction cost expanded and economic inefficiencies. The conclusion is, as the policy’s objective has been achieved, the desulfurization electricity price policy in China should be cancelled. The way of reducing pollutants emission in the form of price subsidies cannot be extended to other pollutants or other industries emission control.

The experimental test for evaluating the heat extraction performance for a deep Downhole Heat Exchanger (DHE) was carefully designed and performed in the last winter in Tanggu area, Tianjin, China. The test well in which DHE was installed had been used as a reinjection well for two years. The reservoir temperature at the bottom permeable layer of the well decreased to a maximum temperature of 51℃ from its original of 64℃ due to the reinjection of cold water. Up the reinjected cold water layer, there is an bedrock layer that has a geothermal gradient approximately of 2℃ per 100 meters deep. A novel DHE configuration was designed and constructed in the test. The results show that the new DHE configuration works very well for extracting heat from a deep geothermal reservoir. The stable outlet temperature and the thermal power from the deep DHE can be reached after continuously heat extracting in about 2 weeks. The maximum heating power according to the test data is about 270 kW, which is much larger than some theoretically calculated values of deep Borehole Heat Exchanger (DBHE) using the existing conduction model.

A natural draft hybrid cooling system (NDHCs), which combines the benefits both for wet cooling and dry cooling, is proposed for thermal power generation with insufficient and unsteady cooling water source. An iterative calculation method is developed based on the physico-mathematical models to predict the performance of this system. Taking a natural draft dry cooling tower (NDDCT) suitable for 300MW power plant as object, the effect of water distribution of the dry and wet sections is investigated in the final part. It can be concluded this reformed system can reach a more flexible operation mode for complex environmental conditions.

As the major energy consumer and carbon emitter, the power sector accounts for 40% of total carbon emissions in China in 2011. Understanding provincial-level driving mechanisms of CO2 emissions in power sector is vital for achieving China’s national carbon emissions reduction targets in 2030. To understand the critical provinces and driving forces of CO2 emissions in power sector, this paper firstly derives seven different driving factors based on the logarithmic mean Divisia index (LMDI) decomposition model. The provincial-level CO2 emissions in thermal power sectors are calculated from 2004 to 2014. Then, we analyze the CO2 emissions growth ratio of each province, provincial-level change rate of contribution and positive or negative contributions of the emission dynamics for each driving force. The main results show that the power sector of Inner Mongolia and Jiangsu contribute a lot to national CO2 emissions. The change of CO2 emissions of power sector is bigger in developing provinces compared to that in developed provinces. Based on provincial the CO2 emissions changes and total amounts, more carbon emission reduction policy should be implanted in Inner Mongolia, Xinjiang, Anhui, Jiangsu and Ningxia. In addition, the economic scale, industrial intensity and energy intensity are the critical driving forces for total carbon emission. By investigating the critical driving forces and their contributions in critical provinces, this paper aims to provide theoretical foundations for decarbonizing power sector.

This paper aims to evaluate severe accident in VVER-1200. The consequences of severe accident depend greatly on containment safety features and its performance in retaining radioactive material. The specific type of LOCA includes hot leg or cold leg break in the primary coolant circuit. For both simulations a loss of offsite power is also initiated after 500 seconds. It shows that the Reactor Cooling System (RCS) pressure drops from 155 bars to below 5 bars in both the cases to reduce RCS leakage. Reactor Core Thermal Power, Nuclear Flux Power and Turbine Load fall significantly after 23.5 seconds because of the occurrence of Reactor Trip. Both HA-1 and HPI are activated to prevent Core damage. The flow of HPI drops to zero after the loss of offsite power. The temperature of the fuel falls below 200 oC within 150-200 seconds of the malfunction in both the cases. The corresponding pressure, temperature, void fraction of reactor etc. are analysed in this paper. The results obtained satisfactorily meet all PSAR (Preliminary Safety Assessment Report) data regarding Loss of Coolant Accident (LOCA). The results provide useful information about safety features of VVER-1200 in case of Loss of Coolant Accident (LOCA) concurrent with loss of offsite power.

Due to the obvious different characteristics of multi-energy power sources, it is necessary to take into account the economic and safety requirements of the power grid at the same time to achieve optimal operation strategy (OOS). This paper focuses on the OOS of multi-energy power system (MEPS), which contains wind power, cascade hydropower, thermal power, and pumped-storage power. Considering the complementary coordinationc characteristics of different types of energy, a completed set of day-ahead coordinated and optimized operating models of MEPS is established, with multiple optimization objectives of maximizing the safety, economy and renewable energy consumption. In order to solve this complex multi-objective problem, a three-stage solution method based on Benders decomposition is proposed. Through decoupling the safety object and economic object of MEPS, efficient solution of the OOS is achieved. The digital simulation discusses the influence of factors such as the diversity of natural scenarios and the safety requirements of the system operation, and simulation results verify the effectiveness of proposed strategy.

The paper presents innovative technological concepts of integrated energy supply schemes based on joint operation of thermal and wind power plants. The main advantage of these systems lies in the improving the efficiency, reliability and environmental friendliness of energy supply (electricity and heat). This is a result of fuel saving and reduction in CO2 emissions from thermal power plants, which becomes possible when part of fuel is replaced with electric power generated by wind turbines. The technological advantages of the proposed schemes are considered. These advantages expand the range of applications for the technologies both in small-scale and large-scale energy systems. A patent protects the proposed technologies.

The exploration of the moon and the construction of the manned lunar outpost are the important parts of the deep space exploration. The continuous supply of thermal energy and power for deep space explorers and scientific equipment is a crucial issue to accomplish manned lunar missions. For most locations on the lunar surface, darkness lasts for periods of about 350 hours, so it is a great challenge for the solar photovoltaic cells and radioisotope thermoelectric generators to launch too much material from Earth. In the mission of manned deep space exploration, it is very necessary to utilize in situ resource effectively and sufficiently to reduce the hardware must be brought from Earth and to meet the requirement of energy and life support system. This paper describes an exergy analysis of a lunar based solar thermal power system using the method of finite-time thermodynamics. The calculations indicate that the system can provide the desired energy for the equipment. The aim of this article is to provide the basis for the design of a solar-powered Stirling engine using thermal energy from the processed lunar regolith.

Rapid growth in the global economy and developments increases the energy demands and 80% of the primary energy demand satisfies by fossil fuels. Extensive utilization of fossil fuels and the paucity of precautionary measurements creates two major challenges one environmental pollution and second future energy crises. Contemplating the serious, issues we have to move our energy demands to renewable and sustainable sources, which have less impact on the environment and sustainable. This article presents optimization techniques by using MATLAB toolbox YALMIP and Interior Point Optimizer IPOPT nonlinear programming to achieve multiple objectives one minimize the operational and fuel cost of the thermal power plant. Second, maximize the benefits of solar and wind power by decreasing the discard solar and wind power. In our optimized model, we perform short-term 24-hour scheduling and operation of four-cascaded hydropower reservoirs optimally combine with three thermal power unit’s one wind power plant and one solar power plant, which balance the active power generation with power demand. The result we obtained shows that a significant difference in thermal cost ($), discard power and CPU time of both tolls FMINCON and IPOPT. Discussion on renewable energy sources their impact on the environment and their tendency (2013 to 2017). In the end, calculations are perform for CO2 emission and reduction of the proposed model and compared the results with different scenarios of case 1 to case 5. Results show eloquence contribution of renewable energy sources and their aftermath on the environment and sustainable.

Since the power load regulation capability of the combined heat and power (CHP) generation plant is weaker than that of the conventional thermal power plant, it is of great significance to decouple the strong relation between electricity generation and heat supply. The thermal heat storage performance of the water thermocline heat storage tank designed to apply to the CHP plant is presented. The tank is supposed to charge heat by heat exchanger with the steam turbine extraction and provide hot water to the heat-supply grid directly. By experiments, the static and dynamic characteristics of the thermocline is studied and some regular patterns are discussed, followed by an effective method to reduce the thermocline expansion, which may be useful for the design and operation of the thermocline heat storage tank.

In modern power systems, the penetration of renewable energy sources, such as photovoltaics and wind power generation, are increasing. Renewable energy is regard as an important role in improving energy shortages. However, renewable energy would cause a high variation of net load. To reduce the high variation of net load, flexibility expansion in the generation-side is one of the solutions. This work discusses the flexibility capabilities of typical thermal power plants, particularly about the combine cycle gas turbine (CCGT) and internal combustion engines (ICE), because both of them can start up in a short time. In addition, this work also discusses about understanding these units’ flexibility as well as other capabilities, such as greenhouse gas emissions, power generation costs, and efficiency.

The implementation of replacing fossil energy with electricity is an effective measure to prevent and control haze, and it plays an extremely important role in realizing the sustainable development of the economy. Guangxi Power Grid Co., Ltd. responds positively to the national call and proposes to promote the implementation of electricity substitution in Guangxi during the 13th Five-Year. This policy can reduce both the environmental pollution and Guangxi’s dependence on foreign fossil energy. Based on the plan of Guangxi Power Grid Co., Ltd., the effects of electricity substitution implementation are studied in this paper by using 2012 Input-Output (IO) table of Guangxi. The main conclusions are as follows: 1. electricity price increment will affect the prices of other sectors, CPI and GDP deflator, which means that the electricity sector occupies an important position in Guangxi’s economy; 2. electricity substitution reduces the use of coal and oil indeed, but the electricity generation structure has been dominated by thermal power so far, so the consumption of electricity still implies certain environmental costs.

Biogas upgrading to biomethane has received particular attention in recent years as a key strategy to produce a natural gas-substitute from biomass. Among the available upgrading technologies, amine-based absorption is an interesting option because of its low electric power consumption and very high methane recovery rates. This paper assesses the energy and economic performance of a biogas upgrading process involving chemical absorption with two different aqueous solvent formulations: 50%w MDEA and a 20%w/20%w MDEA/MEA blend. The process performance is evaluated with Aspen Plus and the optimal process conditions are determined with a multi-objective optimization approach targeting the maximum efficiency and minimum specific equipment cost. In the proposed scheme, to make the system energy-self-sufficient, an internal combustion engine burns a fraction of the raw biogas stream to co-generate both the electric power for the upgrading process and the thermal power required for solvent regeneration. Aqueous MDEA turns out to be more efficient (Pareto dominant curve) and less expensive than the MDEA/MEA blend, as a result of the lower regeneration energy (0.94 kJ/Nm3BM/h vs 1.43 kJ/Nm3BM/h) which yields to lower energy consumptions and smaller engine sizes. Even though the cost estimates are subject to a higher degree of uncertainty, the MDEA option features an expected specific total equipment cost as low as 1,550 €/(Nm3BM/h)) vs. 1,850 €/(Nm3BM/h)) for the MDEA/MEA blend.

In this paper the financial viability of a novel storage concept, referred to as ‘integrated pumped-heat-electricity storage’, is assessed for both a coal-fired and a combined cycle (CC) power plant located in Germany, as well as for a concentrated solar power (CSP) plant located in Spain. The rationale of this concept is to use electricity during times of cheap wholesale market prices, e.g. stemming from a high supply of renewable energies, in order to generate thermal energy via a heat pump, since thermal energy can be stored at comparatively low cost. If the electricity demand rises again, the stored thermal energy is used to power a conventional water-steam cycle, thereby reducing the amount of fossil fuels used or enlarging the operating time of a CSP plant. A mixed integer linear program, considering the day-ahead wholesale market electricity prices and remunerations of offering tertiary control power in Germany, is employed to find an approximation of the optimal schedule for the generation in the power plant as well as for the purchase and the sale of electricity. The financial viability is assessed using net present value (NPV) and real options analysis. Storing electricity to profit from temporal arbitrage is found to be unprofitable, since the (conservatively estimated) costs of thermal storage units are still too high. The largest part of the revenues stems from the remunerations of offering tertiary control power. Therefore, while the utilization of heat pumps, which are estimated to have rather high costs, is not profitable, employing electric heaters without storage units is found to be economically viable for a coal-fired and a CC power plant in Germany. Here, NPV and real options analysis yield the same result, i.e. to invest immediately in such an application. In Spain, offering tertiary control power is presently not remunerated, but only the call-offs of tertiary control energy, which are not considered in the mixed integer linear program. Consequently, employing electric heaters in CSP plants in Spain is found to be not financially viable either.

This paper compares the predicted organic Rankine cycle performance of two low global warming potential working fluids, R1234yf and R1234ze, alternatives to R134a over a wide range of evaporating temperatures and condensing temperatures for a given thermal power input. The results show that R1234yf would require 18.3% to 25.8% higher pump power and would enable up to 13.9% lower net cycle efficiencies than R134a over the range of cycle conditions examined in this work. In the other hand, R1234ze would require 15.7% to 20.2% lower pump power and would enable up to 13.8% higher net cycle efficiencies than R134a, over the range of cycle conditions analyzed. Both alternative fluids net cycle efficiency is benefitted substantially by a recuperator. The differences with R134a in net cycle efficiency are accentuated for high evaporating and condensing temperatures.

Ocean Thermal Energy Conversion (OTEC) power plants use the natural temperature differences found in the ocean of tropical regions to drive turbines that create electricity. A thermal compressor (injector) applied in a power cycle allows extension of expansion of a working fluid. Therefore, the unique feature of the Injection Power Cycle (IPC) is that the maximal temperature difference of the working fluid in a power cycle is greater than the temperature difference between a heat source and a heat sink. This results in the increase of pressure drop and technical work of the working fluid during its expansion. Furthermore, the OTEC power can be used: • for seawater desalination and production of enough potable water to support large populations located near the coast and • to produce energy carriers such as Hydrogen (stored in HYDRNOL: Organic Liquid Storage), which can be shipped to areas not close to OTEC resources. This could be fuel for thermal power plants, as well as for internal combustion vehicles, such as gas turbines and reciprocating engines. The ability to store and transport hydrogen within a liquid carrier at standard (room) temperature and atmospheric pressure provides many advantages over current hydrogen storage methods. The need for large, heavy storage tanks is eliminated. Major changes in the fuelling infrastructure of the world are avoided. The risk for explosion is minimized since the hydrogen is stored within a molecule and not in its elemental form. Furthermore, it is less flammable than gasoline or diesel. Also, HYDRANOL is cost effective when compared to traditional (fossil) fuels.

Waste heat recovery systems such as the Organic Rankine Cycle (ORC) face the challenge of being subordinated to the main process, and therefore they are not allowed to control the heat source as conventional power systems. Because of the conceivable fluctuating characteristic of the heat source the dynamic response of the system has to be analyzed. The component of major importance for the dynamics of the system is the evaporator, because it links the heat source to the ORC. Although different dynamic models of heat exchangers for ORC are available in literature, researchers have hardly focused their attention on a thorough analysis of the key factors that affect the evaporator dynamics. In particular, the influence of the evaporator geometry and materials is analyzed in this work. A characterization approach based on the main heat exchanger construction parameters is carried out in order to predict the evaporator response time and how it is affected by those design factors. With the help of dynamic simulations, the approach is applied to a real kettle boiler geometry. Possible improvements in the heat exchanger geometry that can lead to a dynamically more robust system and buffering some of the intermittency of the heat source are foreseen. Published version

There is a significant number of Greek islands in the Aegean Sea that still meet their electricity demand on the basis of the local autonomous thermal power stations, using considerable amounts of imported oil. In addition, many of these islands suffer from water scarcity, covering their potable water needs with water imports at extremely high costs. Under the framework of PHAROS research project, and in an effort to support energy and water self-sufficiency, an integrated software tool has been developed for the optimal planning of hybrid renewable energy systems (HRES), capable of investigating the energy balance of autonomous island regions. In this context, a planning methodology for HRES combined with a sizing algorithm for desalination plants were devised and integrated in the advanced software tool named Energy System Analysis (ESA). ESA enables the detailed analysis of systems that include components such as wind, PV and desalination plants, energy storage devices and diesel engines. To this end, the long-lasting problems of the Aegean Sea islands, mainly stemming from their state of remoteness and isolation, require the examination of long-term energy strategies, which ESA can support in an efficient manner. In this context, the current work provides a short presentation of the ESA tool main features, using two discrete case studies that correspond to a North and a South Aegean Sea island respectively.

The work discusses a problem of harvesting and upgrading of ultra-low grade heat with thermochemical energy storage technology for space and domestic water heating in residential area. The laboratory scale prototype, operating on the principle of an open packed bed sorption reactor and using moist air as a heat/mass transfer fluid, is experimented. The range of experimental air temperature was set to 17–40 °C, which corresponds to the typical range of domestic waste thermal energy. The tested sorbent was a salt-in-matrix composite material composed of a silica gel containing 43 wt.% of calcium chloride (CaCl2) salt. Hygrothermal behavior and energy performances of the prototype control volume filled with 245 g of material, representing the reactive front of a thermal wave, were analyzed at constant inlet hydration conditions (water vapor pressure of 12.5 mbar). The average temperature lift was recorded as 9–13 °C, representing the amplification of a supplied heat on 23% – 75% depending on the inlet temperature. The average specific thermal power inside the material bed was measured to be 168–267 W kg-1. The apparent energy density, based on the prototype control volume, ranged between 1.0 and 1.6 GJ m-3. Taking into account the heat of water vaporization, the coefficient of performance of the process was determined to be 0.96–1.57.

Due to its inherent large thermal inertia, concrete core activation (CCA) could assist in active demand response schemes. By shifting the injection or extraction of thermal power in time, demand peaks that normally occur more or less simultaneously in clusters of buildings can be spread out in time. Furthermore, thanks to the low temperature differences allowed with respect to the room temperature, CCA is ideally combined with technologies that have increasing renewable potential, such as heat pumps, low temperature district heating and high temperature district cooling. This paper illustrates the flexibility potential of concrete core activation through the exploitation of its thermal energy storage capacity by dynamic simulations. A validated RC thermal model of a CCA is coupled with a detailed building model, including user occupancy and weather disturbances. The flexibility indicator is calculated based on a method presented in the literature, but using an extended version that allows application to more complex systems, including heat losses. Balancing the building between minimal and maximal temperature, the thermal power needed to heat or cool the building can be modulated up- or downward with respect to the reference energy use. The method is applied to various building types with different insulation levels, in order to map the flexibility potential of CCA heating compared to buildings heated with radiators. ispartof: pages:92-104 ispartof: Proceedings of the 11th International Renewable Energy Storage Conference vol:135 pages:92-104 ispartof: International Renewable Energy Storage Conference location:Düsseldorf date:14 Mar - 16 Mar 2017 status: published

Energy storage has become a crucial issue regarding renewable energy management, even more important in an island system with the inherent fluctuating operation and inaccurate energy forecast. The growth of decentralized generation in an isolated electrical grid means load stability problems and requires energy storage as a potential solution to guarantee safety and reliability standards. The study described in this paper highlights the need to store energy in Madeira island system and evaluate the operational power dispatch with the introduction of batteries. A simulation tool was developed to quantify the impact of batteries in wind and thermal power plants technologies.

In this paper, a steam Rankine cycle is proposed for the subsea power supply. The turbine, as the key component, is connected to a power shaft to produce the power output. The pressure at the inner and outside of the turbine shaft seal can be balanced. A mathematical model is established, energy and parametric analysis are applied. The results show that this power cycle can acquire a thermal efficiency of 35% at 5000 meters depth. Besides, the electrical heating temperature and the condensing pressure are the key parameters that dominant the performance of this cycle.

Direct use of a steam heat source for the organic Rankine cycle system is one of the key challenges in various plant industries where low-grade steam is available and is becoming difficult as the parent system has a strong variability. In addition, changing the type of the heat source fluid among steam, hot water, thermal oil and others from the parent plant could increase the operation time of the heat recovery system, which increases system economics and makes it more attractive. Although a variety of ORC systems have been developed mainly using single heat source as hot water heat source or a heat transfer loop. An ORC system with the direct use of a steam heat source has been rarely reported, and a system using two different heat sources have not been reported yet. Here we evaluate the performance characteristics of an ORC system using two different heat source fluids: steam and hot water. The target ORC system was originally developed for the hot water heat source and has a simple cycle configuration with R245fa as working fluid, and is composed of typical four components as: a two-stage radial turbine and a coupled generator, plate-type heat exchangers with a refrigerant tank, and a multi-stage centrifugal pump. The nominal net power output at the design point is 187.9 kW with the turbine expansion ratio of 9.5. The heat exchanger analysis showed that the steam heat source can be applied to this system. The isothermal heat exchange and high heat transfer coefficient at the two-phase region of the steam showed a large overdesign for the current application. We tested the ORC system using a steam generated from an incineration plant. The temperature and pressure of the steam were 143.5℃ and 302 kPa. We showed that the ORC system originally developed for the hot water heat source could be used for the steam heat source without any major system changes.

The performance of a transcritical organic Rankine cycle (TRC) system is affected by the heat source conditions of the exhaust gases resulting from a turbo-expander under off-design conditions. In the present study, the axial-turbo-expander of the TRC system under the design point was designed through 1-D aerodynamic theory and validated using a computational fluid dynamics (CFD) solver. The CFD solver was also used to simulate and analyze the thermal-fluid field of the turbine under various heat source conditions to determine the turbine efficiency under off-design point. The axial-turbo-expander in the TRC system, with R134a serving as the working fluid, was numerically examined to investigate the turbine performance at expander inlet temperatures of 140–115 °C and circulated loop mass flow rates of 15–12.5 kg/s. The results revealed that the isentropic efficiency of the turbine sharply dropped as the circulated loop mass flow rate increased at m w > 14.5 kg/s. However, the isentropic efficiency was only slightly affected by T in_exp at T in_exp > 130°C. In conclusion, the temperature of the circulated loop was increased to fix the mass flow rate of the circulated loop at the increasing thermal power of the exhaust gases due to the isentropic of the turbine slightly affected by the increasing temperature of the heat source. In contrast to the increasing thermal power of the exhaust gases, the mass flow rate of the circulated loop was decreased at the decreasing thermal power of the heat source.

Thanks to various feed-in-tariff programs, aimed to the development of electric energy production from renewable sources, several biomass firing power plants have been realized in Italy in the last few years, contributing to the reduction of greenhouse gas emissions and fossil fuel energy dependence. In particular, during 2012 there was a rush for the completion of several renewable energy conversion power plants, leading up to 986 new plants to get the first connection to the grid (+81,3% with respect to 2011); among those, 80 new plants were solid biomass firing plants (+47,1% with respect to 2011) [1]. Linea Energia S.p.A., the Energy Business Unit of the multiutility company LGH, Linea Group Holding, which operates over the areas of Brescia, Cremona, Crema, Lodi and Pavia, gave its contribution in 2012 with the realization and start-up of two waste wood fueled energy conversion plants located in the Northern Italy, more exactly in Cremona and Rodengo Saiano (Brescia). This paper focuses on the operation and maintenance experience of the waste wood conversion power plant of Cremona, which is capable for a gross electric power production of up to 1.0 MW and a thermal power recovery of up to 5.5 MW. In the first part of this paper a description of the plant is presented, giving an insight of the engineered process. In the second part, the performance analysis of the energy conversion process is discussed by comparing actual performance of the system with the originally defined reference performance. In 2016, as a consequence of the operation of the unit in anomalous conditions (air entering in the system) the turbine blades got scaled. The output of the turbine progressively decreased but was then successfully re-established after an extraordinary maintenance carried out by the turbine supplier.

This article discusses the research conducted on a small CHP ORC system, which has been developed with the aim of using it in single-family houses. The electric and thermal power of the system is 2.5 kW e and 25 kW t , respectively. A working prototype of the system was built in 2014 and since then it has been the subject of different kinds of studies. The results of the preliminary research show that the prototype of the ORC system functions properly and achieves its predicted performance. This research was carried out in laboratory conditions that usually differ from real operating conditions. The article presents the results of further testing intended to verify whether the prototype operates properly under various operating conditions. During the tests, the system’s performance was evaluated based on the changes in such parameters as thermal load, flow rates of the working mediums and electrical load of the turbo generator. In the course of the research, the following parameters were measured: temperatures, pressures, flow rates and electrical parameters associated with the operation of the turbo generator. The obtained results demonstrate that the prototype of the ORC system was able to operate correctly despite abrupt changes in some of these parameters. Furthermore, the safeguards applied to the regulation system protected the safety of people in the vicinity of the installation as well as the installation itself against damage. Lab tests have also shown that the oil-free turbogenerator—equipped with gas bearings—can operate over a wide range of rotational speeds, allowing adjustment of the generated power according to the current energy demand.

In this work the thermal performances of innovative heating devices are analyzed with the help of a numerical model. The innovative devices, Thermosaic Plus and Thermosaic Comfort produced by Xinergia, are first evaluated under the UNI EN 442 conditions. Their performances are then analyzed under conditions closer to the real working ones. The differences in the results of the two analysis are put in evidence. Moreover the performances of the innovative heating devices are compared to those of traditional tubolar ones. Criteria for evaluating the heating device efficiency are also proposed and applied to the analysis, taking the perceived comfort into account. Referring to these criteria, large reductions in the absorbed thermal power are found for the innovative devices with respect to the power required by the traditional tubular ones.

Micro gas turbine applications in concentrating solar field systems is already on industrial stage. The peculiarity of these systems is the possibility to use fossil fuels when solar power source is lacking. It is preferable that the system works in solar-only mode for long time; however, owing to the efficiency loss which occur for low radiation levels, a fuel integration is necessary. This work presents a system which allows to operate with constant efficiency, without the use of fuel for over one fifth of the nominal power rate. It is based on a regenerated micro gas turbine in closed loop configuration. The proposed system includes the solar tower, the heliostats field, the regenerator and a low temperature heat exchanger which cools the working fluid. Finally, two more devices, for the actuation of the proposed control are included: an auxiliary compressor and a bleed valve. The use of air as working fluid has been analyzed, with different values of the base cycle pressure (inlet pressure of the main compressor), which are needed for varying the mass flow flowing in the system. The control of the mass flow rate is mandatory to regulate the gas turbine power, by keeping almost constant the maximum temperature of the thermodynamic cycle when the incident solar radiation changes. In particular, the auxiliary compressor admits fresh air in the cycle when the thermal power received by the sun increases, while the bleed valve discharges it in the atmosphere, when the thermal power decreases. Therefore, the thermodynamic cycle is unchanged and guarantees constant net system efficiency for all the operations conditions. Particular attention is given to the receiver thermal incident flux, heliostat field and solar tower design. The current results are compared with the annual efficiency and energy production of an existing plant in hybrid configuration (solar-fuel).The analysis has been carried out on a commercial gas turbine having a power of 100 kW, sited on Seville town. For the heliostat field analysis, the open source code Solar PILOT has been used, while for the entire plant the code Thermoflex has been employed.

In Japan, 53 GW Photovoltaic (PV) systems will be introduced in future electric power system in 2030 year. It will raise issues of insufficient supply capability and reserve capacity to utility operator to ensure supply-demand balance. On the other hand, Microgrid that located in demand side will be expecting to actively response the incentive signal sent by the utility operator so as to contributing to demand-supply adjustment. In this paper, based on revised IEEJ-EAST-10 Generators simulation model that included of 22GW PV generations and 5GW Microgrids, we analyzed the effect and potential contribution capability of microgrid to electric power system demand-supply adjustment in hour-ahead electricity market through Price-Based Demand Response. Firstly, we analyzed the impact of day-ahead market marginal price on optimal scheduling of Micorgrid. Secondly, we analyzed the impact of optimal scheduling of Micorgrid on Utility operator in Hour-ahead market operation. Lastly, we evaluated the contribution capability of microgrid to electric power system demand-supply adjustment in hour-ahead electricity market that included the improvement of partial-load operation of coal thermal power plant, Utility side load-leveling, and reserve capacity provided by Microgrid.

An up-to-date review of CO 2 capture technologies for coal-fired power plants is presented. This study is based on EDF experience on CO 2 capture build through collaborative projects and pilot plants operation follow up. This review focuses mostly on most mature technologies and provides insight on the interest of least developed technology with high potential. Technologies are compared and assessed based on energy performance, maturity and economic criteria. A specific method for assessing uncertainties in this process is proposed. Amine based post-combustion technology remains the best reference for short and medium terms with a tight competition with cryogenic oxy-combustion. Both share the highest maturity and similar energy performance in their most advanced embodiments. At the moment IGGC based capture looks less promising for power generation due to the high cost of the plant even without CO 2 capture. Regarding more innovative technology, promising candidates, such as inertial extraction, chemical looping combustion or oxy-fired CO 2 cycle, are highlighted but their effective development up to industrial ground is not guaranteed due to the constant improvement of reference technology and their difficulty to be retrofitted.

To examine the rationale for policy parity of three basic low carbon power sources, the consumer preference for those power sources was evaluated by choice experiment through a public survey in December 2015 - January 2016. A sample with decent representativeness was obtained by two stage stratified sampling and door-to-door canvassing. The choice questions were designed with realistic attributes simulating power retail market starting from April 2016. Through the data analysis, using random parameter logit model, we found that respondents’ WTP shows that they considered not only CO 2 emission reductions but also the characteristics of the three methods of low carbon power generation. It is also found that WTP is 11 yen per 1% increase in renewables, 14 yen per 1% decrease in nuclear (this WTP varies from one individual to another), and 4 yen per 1% increase in thermal power generation with CCS. The results of WTPs for the share of renewables and CCS in the power mix of new electricity retail companies in the future market rationalizes the necessity of policy parity to some extent for those technologies implying inclusion of CCS in the FIT but not nuclear.

To significantly reduce the amount of emission of carbon dioxide (CO2) to the atmosphere, which is a principal cause of climate change (global warming), and to realize a low-carbon society, the introduction of Carbon dioxide Capture and Storage (CCS) into coal-fired power plants is expected to be effective. Emissions from post-combustion CO2 capture plants using amine solution may affect the human health and environment. It is, therefore, important to evaluate the environmental impacts by conducting environmental risk assessment, and to, if necessary, employ emission reduction technologies, for effectively introducing CCS. Case studies on amine emissions from the CO2 capture process and the results of environmental risk assessment are reported. However, there are no guidelines on environmental risk assessment method for the CO2 capture process which enable plant owners to reduce the environmental impact of the process, to increase understanding of local residents (near CO2 capture plants) and public, and to promote the introduction of CCS. In this study, as part of the project by Ministry of the Environment (Japan), Mizuho Information & Research Institute, Inc. (MHIR) and Toshiba Corporation drafted the guidelines presenting the basic principles (methods, basic points) of environmental risk assessment with regard to exhaust gas and other parameters involved in the CO2 capture process. Based on Toshiba's emission data from 10 ton-CO2/day scale pilot plant using MEA solution at Mikawa coal fired thermal power plant, MHIR conducted a trial of environmental risk assessment for the CO2 capture process, examined the risk assessment procedure, and drafted technical guidelines. The guidelines are expected to enable plant owners to make reasonable judgement on “how far emission should be reduced”, and thus to decide “to what extent they should employ emission reduction technologies”. And, the guidelines include “whole-mixture approach”, which not only helps to conquer the issues typical of the CO2 capture process but also is easy to understand and thus familiar to local residents and public.

A new humid air humidifier was designed and built. It is composed with two identical stages. The condensation is achieved on vertical tubes. Many configurations are tested. A thermodynamic model has been established. This model predicted the performances of each stage. The results showed that the flow rate of pure water produced by dehumidification and the exchanged heat power increase with increasing mass flow rates of dry air and cooling water, temperature and absolute humidity of inlet moist air in the dehumidifier. The high quantity of water vapor in air makes a thick film of condensate on cooling tubes. This reduces the flow rate of condensate and thermal power exchanged. So, the use of multistage condenser as dehumidifier is must but not sufficient for optimum efficiency.

Carbon capture and storage (CCS) technologies available in the near-term for pulverized coal-fueled power plants (i.e., post combustion solvent technologies) require substantial capital investment and result in marked decrease in electricity available for sale to the grid. The impact to overall plant economics can be mitigated for new plant designs (where the entire plant can be optimized around the CCS system). However, existing coal-fueled power plants were designed without the knowledge or intent to retrofit a CCS process, and it is simply not possible to re-engineer an existing plant in a manner that it could achieve the same performance as if it was originally designed and optimized for CCS technology. Pairing an auxiliary steam supply to the capture system is a technically feasible option to mitigate the derate resulting from diverting steam away from an existing steam turbine and continuing to run that turbine at steam flow rates and properties outside of the original design specifications. The results of this analysis strongly support the merits of meeting the steam and power requirements for a retrofitted post-combustion solvent based carbon dioxide (CO 2 ) capture system with an auxiliary combined heat and power (CHP) plant rather than robbing the base plant (i.e., diverting steam from the existing steam cycle and electricity from sale to the grid).

In this study, thermal efficiency of power plant has been evaluated by integrating the KIER-developed dry-sorbent CO 2 capture process (KIERDRY) with a pulverized coal-fired power plant using a commercial simulator, gPROMS. A simple basic KIERDRY model has been developed and connected it to PCPP (Pulverized Coal Power Plant) example in gCCS, a system modelling tool for support of design and operating decisions across the CCS chain. The PCPP capacity of 500 MWe and the KIERDRY capacity of 150 MW (125 tonCO 2 /hr based on captured amount) have been set as a base case. We consider HP steam(307 o C, 31 bar) and IP steam(461 o C, 14∼14.6 bar) as the utility steam of a regenerator in KIERDRY since the steam condition of a regenerator has been set to approximately 14.6∼15 bar, saturated. Totally 5 cases have been evaluated: (1-1) Use HP steam, use condensate to make a process steam, and return to condensate(1 bar); (1-2) Use HP steam and return to 5th feed water heater(12 bar); (2-1) Use IP steam, use condensate to make a process steam, and return to condensate(1 bar); (2-2) Use IP steam and return to 5th feed water heater(12 bar); (2-3) Use IP steam, do additional heat integration by preheating dry sorbents at loop-seal, and return to 5th feed water heater(12 bar). As a result, the condensate generated at the regenerator should be returned to the power plant rather than used to make a process steam, which is supplied as a reactant for the carbonation reaction. Based on several case studies, the reduction of the power output of the PCPP with KIERDRY has been varied from 29.2 MWe(minimum penalty) to 71.7 MWe(maximum penalty). Thus, it can be concluded that the energy penalty of KIERDRY has been significantly reduced by how heat has been integrated with PCPP.

CO2 reduction has become an urgent need due to the greenhouse effect. Scientists working on the topic agree that the major cause of global warming is greenhouse gases emitted due to human activities. Burning of fossil fuels is one of the main reasons. Using a solid sorbent to capture CO2 at high temperature is a concept which is now being widely considered to reduce CO2 emissions. Capture from flue gas by calcium looping (CaL) may be an attractive alternative due to cheap and readily available sorbent (limestone). CaL may reduce considerably the energy penalty represented by the capture system. A significant transfer of thermal energy is required for the endothermic calcination process. In first generation CaL, the heat is transferred directly by oxy-combustion in the calciner; pure oxygen is then required as the oxidizer to avoid mixing CO2 with N2, and the energy required to produce oxygen gives an unwanted energy penalty. CaL technology would be an even more attractive alternative for the thermal power industry if the heat could be transferred indirectly to the calciner. By high-temperature integration between the CO2 capture plant and the power plant, the energy penalty associated with oxy-combustion would be avoided. In this work, Aspen Plus® is used to simulate the CaL process with indirect heat transfer applying different indirect heat transfer concepts. Six different cases are studied and the results are discussed. It has confirmed such a scheme could give an energy penalty lower than for example amine scrubbing or oxy-combustion.

Liquid amine scrubbing has been widely and intensively investigated at demonstration scale to capture CO 2 at mass CO 2 emission sources, such as thermal power plants and steelworks. However, CO 2 regeneration process in a desorber is energy intensive, which limits implementation of this capture technology. Herein we propose an alternative CO 2 capture method by electrodialysis. CO 2 in a flue gas or blast furnace is trapped in aqueous K 2 CO 3 , and the resulting solution is condensed by electrodialysis. The trapped CO 2 is finally recovered under vacuum. This technique can significantly reduce the required energy to capture CO 2 in comparison to the current technology.

This paper presents a model of a Ca-looping CCS system that is applied on a reference conventional lignite coal fired power plant. The gross electric power output of the reference plant is 250 MWe, with coal consumption 214 t/h and corresponding CO2 production 211 t/h. The Ca-looping system is considered as a retrofit of this power plant. The general model of the power plant balance is connected with a detailed model of the Ca-looping system, consisting of two separated models of carbonator and calciner. The model of a circulating fluidized bed type carbonator is the main part of the model and includes modelling of the fluidized bed hydrodynamics and the chemistry of the CO2 reaction with the limestone sorbent. Two cases for 71 and 87% CO2 capture are modelled. The outputs of the model show material flows and energy inputs and outputs of the Ca-looping system and dimensions of the calciner in the Ca-L system. Generally, required thermal power input for the Ca-looping system integrated is about 50-70% of the power input of the original power plant, offering about 300 MW thermal power that is utilizable for additional electricity production.

The Canadian federal government has introduced carbon dioxide emission intensity limits of no greater than 420 kg/MWh net for new coal plants and existing coal plants more than 50 years of age. Many operating coal plants in Canada will be impacted by this legislation in the near future, requiring operators to plan a compliance strategy. The Canadian Clean Power Coalition (CCPC) investigated the performance and economics of a number of options for existing plants that could deliver compliant solutions. These options included strategies in which natural gas is available and some in which only coal firing is feasible due to cost or logistical issues. Repowering and post-combustion capture (PCC) options were studied using an eastern Canadian power plant firing bituminous coal. The base-case (BC) option was a new combined-cycle gas turbine (CCGT) plant, against which all other options were compared. The following cases were investigated: 1. PCC using: a. Monoethanolamine MEA solvent with crossover steam regeneration b. Commercial advanced solvent with crossover steam regeneration c. Commercial advanced solvent with a small gas turbine (GT) and a low-pressure steam generator d. Commercial advanced solvent with a GT, triple-pressure heat recovery steam generator (HRSG) and a back pressure steam turbine e. Commercial advanced solvent with a natural gas boiler and a back pressure steam turbine 2. Repowering of existing steam turbines with new a GT and HRSG 3. Repowering of existing steam turbines with fuel cells a. New solid oxide fuel cell (SOFC) topping unit b. New molten carbonate fuel cell (MCFC) topping unit 4. Expanded PCC approach with: a. Third unit with full LP steam turbine bypass supplying steam to PCC b. Circulating fluidized bed (CFB) boiler and back pressure steam turbine One of the issues with incorporating PCC in an existing facility is delivering the thermal regeneration energy to the PCC reboilers in an efficient and cost-effective manner. This can involve significant integration with the low-pressure stages of the steam turbine, a duty for which the turbine was not designed. Because turbine modifications (to deliver partially expanded steam to the PCC plant) can be costly and would require significant down time, alternative strategies were investigated in which the PCC facility would effectively be a “standalone” facility, with the main plant interfaces being the flue gas to be treated and some shared services. The costing analysis was carried out on the following basis: 30-year plant design life (with life-extension costs included for existing plant), 90% capacity factor for the first year cost of electricity (COE), and a coal cost of $4.73/GJ and a natural gas cost of $10.00/GJ (based on 2013 forecasted costs). Case 2 (repowering existing steam turbines with new natural gas combined-cycle plant) without any additional CO2 abatement, delivered both the lowest capital costs and cost of electricity. If the existing coal boiler plant remains operational, the lowest costs were achieved by installing a molten carbonate fuel cell (Case 3b) followed closely with an advanced solvent PCC unit with solvent regeneration thermal energy being delivered by an efficient, small, dedicated gas turbine with a triple pressure HRSG (Case 1d). Where there is no existing infrastructure to deliver natural gas, the traditional methodology of extracting crossover steam from the unit for PCC solvent regeneration proved to be the lowest-cost option.

Increasing penetration of intermittent renewable energy production in power systems will remarkably increase the need of flexible and controllable power generation. Subsidised renewable generation has revolutionized energy markets and brought down electricity prices leading to lack of investments to new controllable generation plants. As numerous existing thermal power generation units have been closed down, there is no doubt that all the possible flexibility available in power systems should be harnessed to stabilize the power systems. Combined heat and power (CHP) generation is widely used in district heating (DH) systems. As total heat production into the DH network needs to be balanced with the total heat consumption, this sets significant limitations to the long term power production. However, the coupling between the heat load and electric production can be decoupled temporarily by using the heat storage capacity of DH network consisting of network volume and optional heat accumulators. This paper presents the results of research work dealing with the analysis of dynamic operability of interconnected CHP plants and district heating networks. The flexibility of generation capacity was compared with the requirements set to power producers to be able to participate the Automatic Frequency Restoration Reserve (FRR-A) market. For that, two case studies were presented that include FRR-A tests in two municipal CHP plants that utilize a heat only boiler and a DH accumulator to balance the heat production variations that are caused by changes in power production. The results indicate that both cases fulfil the requirements and that the DH network operation is affected only slightly. However, the rapid power level change is a disturbance to CHP boilers and DH networks that the process components and automation systems must adapt to. Therefore these aspects must be considered carefully when applying such new operation practises in existing CHP plants. publishedVersion

Air pollution is one of the major problem in China's power sector. This paper calculates the baseline emission factor in the power sector and uses the index decomposition method to analyze the variation trend of the emission factor. For the SO 2 , the simple average baseline emission factor is 1.15 kg/MWh. The east China has the highest emission factor and the central has the lowest number. As for the NOx, the simple average is 1.76 kg/MWh, the northeast China has the highest emission factor, and the South China has the lowest emission factor. And the decomposition analysis takes into account three driving factors: pollution control technology level, fuel mix and power structure. The variation from 2005 to 2013 of the SO 2 baseline emission factor is mostly influenced by the pollutant control technology improvement, and fuel mix in thermal power industry makes small contribution on the emission reduction and the influence brought by fuel mix varies a lot among different regions. As for the variation of NOx emission factor from 2007 to 2013, the technology level causes biggest variation too. The fuel mix also makes some positive contribution on east and central China. And the power structure don’t have significant influence on the variation of both SO 2 and NOx baseline emission factor.

Based on the present situation of water consumption, this paper analyzes the factors affecting the selection of water technologies in the thermal power industry in China. Based on the water consumption standards and water conservation indicators in 345 thermal power plants nationwide, analysis showed the water consumption of thermal power plants would still have some water conservation potential, and the water required for generating one unit of electric power differs in different regions. Based on analysis of the water conservation technologies widely adopted in the thermal power industry currently, we selected 18 types of water conservation techniques within 6 categories and recommended their nationwide promotion. To ensure the sustainability of regional water resources and energy, we analyzed the future trends of development of water conservation technologies in the domestic thermal power industry and proposed relevant policy recommendations for the development of the thermal power industry and the management of water conservation techniques.

Smart energy systems are complex systems (i.e. composed of windmills, PV panels, solar collectors, heat pumps, CHP systems, etc) in which synergies rise through the ICT (Information and Communications Technology) based management and control of the whole system. In the development of efficient smart energy systems, a fundamental step is the optimization of total energy conversion, transmission and utilization processes within the whole system. To this extent, mathematical models can represent very useful tools for the simulation of the behavior of the system. In this paper, a library for the dynamic simulation of smart energy systems is presented. The library is implemented in Matlab ® /Simulink ® and each component (i.e. the energy conversion and distribution systems and the end-users) is developed through a modular approach. Therefore, the modules are designed by considering a standardized input/output and causality structure. Finally, the capabilities of this approach are evaluated through the application to the district heating and cooling network of the Campus of the University of Parma. The case study is based on a branch which feeds twelve buildings with a total heating volume of about 150 000 m 3 and peak thermal power demand of about 8 MW. Results reported in the paper demonstrate the effectiveness of this approach and the capability in term of system optimization.

In order to realize low-carbon development, and strive to complete the carbon emissions reduction targets of “13th Five-Year”, this paper takes the national first batch of low-carbon pilot provinces-Guangdong Province as an example, to explore the precise algorithm of carbon emissions from coal-fired power plants. In this algorithm, the calculation formula of fuel characteristic coefficient β is fitted out by the proximate analysis data of fuel, and the content of CO 2 in flue gas is calculated by using the fuel characteristic coefficient. Then the carbon emissions is calculated according to the total amount of smoke. Finally, the algorithm is verified by taking a thermal power plant in Guangzhou as an example, and compared with the IPCC algorithm and the method of coal consumption rate of power supply respectively, which verifies the accuracy of this algorithm.

A new energy-loss analysis based on multifactor disturbance theory was studied in this paper. Due to the strong coupling characteristic of steam turbine system, the disturbance factors were decoupled and categorized. The main steam pressure, main steam temperature, reheat steam temperature and exhaust steam pressure were categorized as the large independent disturbance factors, while the terminal temperature differences (TTDs) of the regenerative heaters were categorized as small independent disturbance factors. The single-factor calculation method for energy-loss of heater TTDs neglected the interaction between each heater, thus all heater should be considered as a whole system when calculating the energy-loss of TTDs changes. The energy-loss of large independent disturbance was calculated based on global variable condition calculation method. Through calculating the energy-loss caused by the classified disturbance factors, the relative errors between the theoretical value and operation value were -3.00% for100%THA (turbine heat acceptance), -9.75 for 75%THA and 16.47% for 50%THA. The relative errors meet the requirements of the onsite guidance.